<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <title>后盾人</title>
  </head>
  <body></body>
  <script>
    // let a = {};
    // let b = {
    //   __proto__: a
    // };
    // let c = {
    //   __proto__: b
    // };
    // console.log(a.isPrototypeOf(b));
    // console.log(a.isPrototypeOf(c));
    // console.log(c.isPrototypeOf(b));
    class Common {}
    class User extends Common {}
    class Admin extends User {}
    let hd = new Admin();
    console.log(Admin.prototype.isPrototypeOf(hd));
    console.log(Common.prototype.isPrototypeOf(hd));

    console.log(hd instanceof Common);
  </script>
</html>
